U.S. patent number 4,901,798 [Application Number 07/226,264] was granted by the patent office on 1990-02-20 for apparatus and method for removal of accumulated liquids in hydrocarbon producing wells.
Invention is credited to Mahmood Amani.
United States Patent |
4,901,798 |
Amani |
* February 20, 1990 |
Apparatus and method for removal of accumulated liquids in
hydrocarbon producing wells
Abstract
A method and apparatus are disclosed to detect periodic well
loading by produced accumulated secondary fluids, and accordingly
to remove the undesired secondary fluid from the tubing of a
hydrocarbon producing well. The method according to the present
invention employs a surface control system that controls the
operation of the fluid removal cycle, and the production cycle of
the hydrocarbon producing well. Periodically, the well is "shut-in"
and upper and lower flow control valves, connected at a
predetermined depth to the well tubing, are actuated to a closed
position to form an accumulation chamber within the tubing. The
closed flow control valves block off the fluid in the accumulation
chamber formed in the lower portion of the tubing string, which
contains the undesired accumulated secondary fluids. A supply line
is used to inject pressurized gas from the surface of the well into
the accumulation chamber to provide the necessary pressure to force
the accumulated secondary fluids, trapped in the accumulation
chamber, through a relief valve and into the annulus of the well
casing thereby removing the undesired secondary fluids from the
well tubing. The controller then stops the flow of the injected gas
to the supply line to stop the removal cycle. The supply line
pressure is relieved, and the pressure across the flow control
valves are equalized. The flow control valves are then opened and
the producing well is returned to production with reduced back
pressure due to the removal of the undesired, accumulated secondary
fluids from the tubing.
Inventors: |
Amani; Mahmood (Kingsville,
TX) |
[*] Notice: |
The portion of the term of this patent
subsequent to December 20, 2005 has been disclaimed. |
Family
ID: |
22848210 |
Appl.
No.: |
07/226,264 |
Filed: |
July 29, 1988 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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867191 |
May 27, 1986 |
4791990 |
|
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|
Current U.S.
Class: |
166/311; 166/322;
166/372; 417/120; 417/143; 166/53; 166/324; 166/373; 417/132 |
Current CPC
Class: |
E21B
43/122 (20130101); E21B 34/16 (20130101); E21B
34/10 (20130101); E21B 43/123 (20130101); E21B
34/101 (20130101); E21B 43/121 (20130101); E21B
2200/05 (20200501) |
Current International
Class: |
E21B
34/10 (20060101); E21B 34/16 (20060101); E21B
43/12 (20060101); E21B 34/00 (20060101); E21B
034/10 (); E21B 043/12 () |
Field of
Search: |
;166/53,72,250,306,305.1,311,313,322,373-375,369-372,386,332,321
;405/53,59 ;251/62 ;417/118,120,138,142,143 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kisliuk; Bruce M.
Attorney, Agent or Firm: Rose; David A.
Parent Case Text
RELATED APPLICATION
This application is a continuation-in-part application of Serial
No. 867,191, filed May 27, 1986 now U.S. Pat. No. 4,791,990.
Claims
What is claimed:
1. A method of removing accumulated liquids from a hydrocarbon
producing well having a casing with perforations at a producing
formation and perforations at a water bearing formation, said
casing further having a string of well tubing disposed within it,
the method of liquid removal comprising:
(a) sealing off a portion of said casing between a lower
hydrocarbon producing formation and an upper water bearing
formation;
(b) producing well fluids comprising hydrocarbon fluids and
secondary fluids through the well tubing;
(c) providing a first flow control valve connected to the well
tubing below the surface of the earth, said first flow control
valve being normally open to allow well fluid production
therethrough;
(d) providing a supply conduit to supply pressurized gas from a
pressurized gas source to the well tubing, said supply conduit
extending in the annulus between the tubing and the casing of said
producing well and communicating with said well tubing through a
port means below said first flow control valve;
(e) providing a passageway connected to the well tubing, through
which liquid can be forced from the well tubing into the casing
annulus;
(f) providing a second flow control valve means connected to the
well tubing below said passageway to prevent downward flow of
secondary fluids into the hydrocarbon producing formation;
(g) monitoring the pressure within the well tubing during
hydrocarbon fluid production to the surface;
(h) actuating said first flow control valve to its closed position
when said pressure inside the well tubing exceeds a predetermined
amount to encapsulate the fluids in that portion of the well tubing
between the first flow control valve and second flow control valve
means;
(i) injecting pressurized gas through said supply conduit into the
well tubing below the closed closure means of said first flow
control valve to pressurize the fluid therein;
(j) forcing the secondary fluids from the well tubing through said
passageway to the casing annulus with said pressurized gas to
remove said secondary fluid from said well tubing and to displace
said secondary fluids into the water bearing formation above the
hydrocarbon producing formation;
(k) monitoring the pressure inside said well tubing due to the
removal of said secondary fluid from the tubing;
(l) stopping the flow of said pressurized gas into said supply
conduit to stop fluid removal when the pressure in said well tubing
is at a desired level;
(m) opening said first flow control valve; and
(n) opening the well tubing to surface facilities for
production.
2. The method of claim 1 wherein the pressurized gas source for the
supply conduit is nitrogen.
3. The method of claim 1 further including the step of providing
fluid communication below the second flow control valve means to
well tubing above the first control valve means to provide fluid
communication with the producing formation.
4. The method of claim 3 further including the step of preventing
the backflow of fluid from the well tubing above the first control
valve means to the well tubing below the second control valve
means.
5. The method of claim 1 further including the step of passing the
pressure from the formation to the surface while the second control
valve means is closed.
6. A method of removing accumulated liquids from a hydrocarbon
producing well having a casing with perforations at a producing
formation, said casing further having a string of well tubing
disposed within said casing, the method of liquid removal
comprising:
(a) providing upper and lower flow control valves in the well
tubing for forming an accumulation chamber with the well tubing
upon closing said valves;
(b) producing well fluids comprising hydrocarbon fluids and
secondary fluids through the open upper and lower flow control
valves and the string of well tubing communicating with the
hydrocarbon producing formation;
(c) monitoring the accumulation of liquids in the well tubing;
(d) actuating the lower flow control valve to its closed position
when the secondary fluids have accumulated beyond a predetermined
amount;
(e) allowing the secondary fluids to accumulate in the well tubing
above the lower flow control valve;
(f) actuating the upper flow control valve to its closed position
to encapsulate the secondary fluids in the accumulation chamber;
and
(g) injecting pressurized gas through a supply conduit into said
accumulation chamber to pressurize the fluid and force the fluid
outside the well tubing through a valve passage way in the
accumulation chamber.
7. The method according to claim 6 further including biasing the
upper and lower flow control valves to the open position and
pressurizing a control line from the surface to the upper and lower
flow control valves for closing first the lower flow control valve
and then the upper flow control valve.
8. The method of claim 7 further including the step of applying an
opposing pressure to the hydrostatic pressure in said control line
used for actuating the upper and lower flow control valves to
equalize said opposed pressures.
9. The method of claim 6 further including biasing the upper and
lower flow control valves normally open.
10. The method of claim 6 further including monitoring the
accumulation of fluids above the lower flow control valve and
actuating the upper flow control valve after the fluids have
accumulated said predetermined amount.
11. The method of claim 6 further including the step of monitoring
the displacement of the fluids from the accumulation chamber and
opening the upper and lower flow control valves upon
displacement.
12. The method of claim 6 further including equalizing the pressure
across the flow control valves for ease of opening such valves.
13. The method of claim 6 further including inducing fluid pressure
on the flow control valves to assist in opening such valves.
14. An apparatus for attachment to production tubing to remove
liquid which has accumulated in the production tubing from the
production of hydrocarbons, comprising:
(a) first valve means disposed above the point of entry of the
hydrocarbons into the production tubing for preventing the back
flow from the production tubing of hydrocarbons which have entered
the production tubing;
(b) second valve means disposed in the production tubing above said
first valve means for closing the flow bore of the production
tubing and encapsulating the accumulated liquids in that section of
the production tubing between said second valve means and said
first valve means;
(c) gas supply means extending to said section of the production
tubing and communicating with the flow bore of said section for
pressurizing the flow bore within said section;
(d) outlet means disposed in said section for allowing the flow of
the accumulated liquids out of the flow bore of said section of the
production tubing upon pressurization of said section by said gas
supply means; and
(e) bypass means to bypass formation pressure from below said first
valve means to the production tubing above said first valve
means.
15. The apparatus of claim 14 further including a third valve means
to prevent back flow of fluids from the production tubing above
said first valve means to the production tubing below said first
valve means.
16. A method of removing accumulated liquids from a hydrocarbon
producing well having a casing with perforations at a producing
formation and a string of well tubing disposed within the casing,
the method of liquid removal comprising the steps of:
(a) providing upper and lower flow control valves in the well
tubing for forming an accumulation chamber with the well tubing
upon closing the valves;
(b) producing well fluids comprising hydrocarbon fluids and
secondary fluids through the open upper and lower flow control
valves and the string of well tubing communicating with the
hydrocarbon producing formation;
(c) monitoring the accumulation of liquids in the well tubing;
(d) closing the lower flow control valve when secondary fluids have
accumulated beyond a predetermined amount;
(e) preventing pressure build up below the lower flow control valve
by relieving the formation pressure into the well tubing;
(f) allowing the secondary fluids to accumulate in the well tubing
above the lower flow control valve;
(g) closing the upper flow control valve to encapsulate the
secondary fluids in the accumulation chamber; and
(h) injecting pressurized gas through a supply conduit into said
accumulation chamber to pressurize the fluid and force the fluid
through a valve passage way into the casing annulus.
Description
BACKGROUND OF THE INVENTION
This invention relates to a method and apparatus to remove the
accumulated liquids from hydrocarbon producing wells for the
purpose of improving production. Many hydrocarbon producing wells
produce, along with the gas, liquids such as water, oil and
condensate. A mixture of these fluids flows from the producing
formation through casing or tubing to surface facilities. The
liquid is entrained as droplets in the gas flow. Part of this
entrained liquid will drop out of the flow due to insufficient
velocity of the gas and will accumulate in the wellbore. Ultimately
this liquid will build up to a height which will exert a
hydrostatic pressure which may be large enough to reduce the
production rate or completely stop production of the hydrocarbons.
This condition is referred to as "well loading".
It is therefore advantageous to periodically remove or reduce the
accumulated liquid from producing wells. By removing the liquid
which has accumulated in the well, the hydrostatic pressure exerted
by the accumulated liquid against the producing formation pressure
will be reduced. Thus the fluid from the formation will enter the
wellbore at much higher velocity and the gas will carry the
produced liquids to the surface more effectively.
DISCUSSION OF PRIOR ART
In the past, methods have been used to remove the accumulated
liquid in the tubing of a hydrocarbon producing well to improve its
producing capability. One common method has been to allow liquids
to accumulate in a downhole accumulation chamber. The accumulation
chamber may be the well tubing string, the annulus, or an
accumulation means attached to the well tubing. Periodically the
liquid is forced out of the accumulation chamber by gas pressure or
formation pressure and is removed from the well. The accumulation
chamber is bled off in order to allow it to refill, and the process
is repeated. This known method requires a large volume of high
pressure gas to displace the undesired liquid from the tubing,
therefore making the method inefficient or limiting the method to
shallow wells.
U.S. Pat. No. 3,363,692 describes a method in which gas is produced
through the casing annulus space upwardly to the surface. The water
rises under pressure of the hydrocarbon producing formation into
the tubing. When the hydrostatic pressure of the water column in
the tubing overcomes the pressure of the water bearing formation,
the liquid is allowed to pass downwardly through a bypass to enter
a water bearing formation which is open to the well bore. In
another embodiment of the U.S. Pat. No. 3,363,692, hydrocarbons are
produced through the annulus and the tubing is used as a liquid
accumulation chamber. The tubing is vented to the atmosphere so
that the water is able to rise in the tubing to a maximum height. A
timed cycle controller at the surface connects the annulus to the
tubing to provide additional pressure to force the water out of the
tubing for disposal.
Methods such as those disclosed in the prior art have proven to be
ineffective for the following reasons:
1. In many cases the hydrocarbon producing formation pressure is
not sufficient to inject liquids into a water bearing formation at
a desired rate;
2. A low pressure formation produces more effectively through
tubing; and
3. Venting natural gas to the atmosphere is wasteful.
U.S. Pat. No. 2,942,663 describes a method in which the accumulated
liquid in the tubing is first displaced downwardly by forcing a gas
into the top of the well tubing. The forced gas flow is stopped
after the liquid level of the accumulated liquid has been lowered
only part of the way to the desired depth. Liquid is then forced
into the tubing above the gas column until the level of accumulated
liquid below the gas column has been reduced to the desired depth.
This causes the gas column to be further compressed without
increasing the pressure at the well head. The pressure is then
released at the top of the well and the expansion of the gas column
forces the liquid above the column from the well. This method
requires the total volume of the tubing to be filled partly with
natural gas and partly with liquid and pressurized to the
displacement pressure. The time lag between filling and venting the
tubing, and the possibility that the liquid pumped into the tubing
may not be recoverable from the tubing by gas expansion makes this
method ineffective.
The flow control valve of this invention is biased to the open
position. All prior art flow control valves better known as safety
valves are biased to closed position. U.S. Pat. No. 4,378,931 to
Adams discloses a fluid pressure actuated flow control valve which
is not biased to the open or closed positions. Adams discloses a
valve having a spring which is only used as a means to absorb or
impose the closing force to the actuator. Adams does not teach a
valve having resilient urging means to bias the flow control valve
to open position.
Other prior art flow control valves which are controlled by two
hydraulic control lines such as the safety valve described in U.S.
Pat. 4,201,363, utilizes resilient urging means to close the safety
valve in order to accomplish the objectives of a safety valve. The
hydraulically controlled form of the flow control valve of this
invention differs from the prior art in that it utilizes resilient
urging means to bias the flow control valve to the open
position.
The present invention provides an improved apparatus and method to
remove the accumulated liquid(s) from the tubing of a hydrocarbon
producing well by minimizing the volume of pressurized gas required
to displace the undesired liquid from the tubing into the casing
annulus for disposal into a water bearing formation. This invention
also provides a control on the desired frequency to remove
liquid(s) from the tubing of a hydrocarbon producing well.
SUMMARY OF THE INVENTION
The primary object of this invention is to provide an improved
method and apparatus to periodically remove the accumulated liquid
in the tubing of a hydrocarbon producing well to reduce the back
pressure which is exerted on the hydrocarbon producing formation
due to the weight of the accumulated liquid in the tubing.
Another object of this invention is to provide a surface control
system to monitor the back pressure build up which is exerted on
the producing formation due to the accumulation of liquids in the
well tubing and accordingly perform the operation of the liquid
disposal and hydrocarbon production cycles.
Another object is to provide a flow control valve which has
resilient urging means to yieldably move the valve toward an open
position in which the valve may operate in its normal mode. Fluid
pressure transmitted through a pipe extending from the well surface
to the valve acts to move the flow control valve toward its closed
position.
Another object of the invention is to provide a flow control valve
biased to the open position for connection to the well tubing. The
flow control valve has resilient urging means to yieldably move the
valve toward an open position in which the valve may operate in its
normal mode. The closing of the flow control valve is controlled by
induced fluid pressure in a first hydraulic control conduit
extending between the surface and the flow control valve in the
casing annulus. The hydrostatic pressure of fluid in a second
control conduit extending between the surface and the flow control
valve balances the hydrostatic pressure of the fluid in the first
control conduit.
Another object of the invention is to provide pressure equalizing
means to equalize pressure across the closure means of the flow
control valve. The pressure equalizing means is opened in response
to reducing fluid pressure in a supply line, and is closed by
pressurizing the fluid in the supply line.
Another object of this invention is to use the inside volume of a
suitable casing string which is cemented and sealed in a second
well for storing pressurized gas. The pressurized gas stored in the
casing of the second well is used to provide the necessary force to
displace the liquid from the tubing to the casing annulus of the
hydrocarbon producing well.
Other objects, features and advantages of the invention will be
apparent from the drawings, the specification and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, like numerals indicate like parts and illustrative
embodiments of the present invention are shown. For a detailed
description of preferred embodiments of the invention, reference
will be made to the accompanying drawings wherein:
FIG. 1 is an elevational view, partially in section showing the
liquid disposal system of the present invention.
FIG. 2 is an elevational view, partially in section showing another
embodiment of the liquid disposal system of the present
invention.
FIGS. 3 and 4 are elevational views, partially in section, showing
other embodiments of the liquid disposal system illustrated in FIG.
2.
FIG. 5 is an elevational view, partially in section, showing
another embodiment of the present invention having a bypass
means.
FIG. 6 is an elevational view, partially in section, showing the
liquid disposal system of the present invention.
FIGS. 7A and 7B are continuations of a fragmentary elevational
view, partly in cross section, of a flow control valve to control
fluid in the well tubing and is shown in open position.
FIG. 8 is a fragmentary elevational view partly in cross section,
of another form of actuating piston means for the flow control
valve of this invention.
FIG. 9 is a fragmentary elevational view, partially in cross
section, of an alternative actuating piston means for the flow
control valve of this invention.
FIG. 10 is a fragmentary elevational view partly in cross section
of another form of actuating piston means for the flow control
valve of this invention.
FIG. 11 is a fragmentary elevational view partly in cross section
of an equalizing subassembly to equalize pressure across the
closure means of the flow control valve of this invention.
FIGS. 12A and 12B are continuations of a fragmentary elevational
view, partly in cross section, of a flow control valve in the
closed position and its equalizing subassembly in the open
position.
FIG. 13 is a vertical, partly sectional view of an equalizing valve
positioned in a mandrel connected in the well tubing.
FIG. 14 is a cross sectional fragmentary view of an injection
control valve positioned in a mandrel connected in the well tubing
to control injection of pressurized gas into the well tubing.
FIG. 15 is a fragmentary elevational view of a wireline retrievable
flow control valve installed in a well tubing.
FIG. 16 is an elevational view, partially in section, showing an
injection control subassembly.
FIG. 17 is a cross sectional view of a disposal valve positioned in
a mandrel connected in the well tubing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In practicing the apparatus and method of the present invention, a
hydrocarbon producing well is equipped with casing and tubing.
Upper and lower flow control valves are connected to the tubing at
predetermined depths with the upper flow control valve connected to
the tubing above the lower flow control valve.
The upper and lower control valves are normally open allowing fluid
production through the tubing, and when closed create an
accumulation chamber to encapsulate the liquid which accumulates in
the tubing between the valves. A hydrocarbon producing formation,
and an upper water bearing formation are both open to the well
bore. A seal means, such as a packer, is placed between the
hydrocarbon producing formation and the water bearing formation. A
passageway means, such as a relief valve, is connected to the
tubing above the lower flow control valve. A gas supply conduit
extends through the casing annulus from the surface and is
connected to the tubing below the upper flow control valve. The gas
supply line can be secured to the outside of the tubing in the
casing annulus. High pressure gas is delivered through the gas
supply line into the tubing string. Hydrocarbons from the
hydrocarbon producing formation are produced through the tubing and
flow to the surface production facilities. As the hydrocarbons are
produced, other liquids, such as water, re produced which
accumulate in the tubing. Periodically the lower flow control valve
is closed to permit the liquids to accumulate inside the tubing.
The upper flow control valve is closed to encapsulate the liquid
that has accumulated in the accumulation chamber. Pressurized gas
is then introduced through the supply conduit to pressurize the
encapsulated liquid inside the accumulation chamber, i.e. that
portion of the tubing between the flow control valves. The
encapsulated liquid is then forced out of the tubing through a
relief valve into the casing annulus. When the differential
pressure in the accumulation chamber is reduced to the desired
level, removal of the liquid is terminated. At this point, gas
injection to the supply conduit is also terminated. The fluid
pressure across the flow control valves is reduced and the flow
control valves are opened. The producing well is opened to the
surface production facilities with reduced back pressure due to the
removal of the accumulated liquid from the tubing. In this method,
a controller system is provided to control the closing and opening
of the surface and subsurface valves. The controller may operate
based on the fluid differential pressure inside the well tubing or
the controller may be a timer which controls the sequence of
opening and closing of the valves on regularly timed cycles.
In another embodiment of the invention, a water bearing formation
may be located below the hydrocarbon producing formation. This
embodiment is similar to the method described above, except that
two packers and a bypass tube are used. The liquid is forced from
the tubing into the casing annulus as previously described. When
the liquid in the casing annulus rises to a sufficient height to
overcome the pressure exerted by the water bearing formation, it is
allowed to pass downwardly through the bypass tube to the water
bearing formation. This alternative method allows the volume of
pressurized gas required to displace liquids from the tubing into
the casing annulus to be minimized because a smaller volume is
required to be pressurized to force the liquid from the tubing to
the casing annulus. Therefore, gas compression cost and the time
lag between filling and venting the tubing are reduced.
Referring initially to FIG. 1, there is illustrated a hydrocarbon
producing well A having a conventional casing 103 with perforations
101 providing fluid communication between the producing formation
100 and the interior of the casing 103. A tubing string 104 extends
inside the casing 103, and a conventional packer 102 seals the
lower part of the casing annulus about the tubing string 104. The
hydrocarbon fluids are produced to the surface through tubing 104.
Well B has a suitable string of casing 140 which is cemented and
sealed to form, in effect, a pressure vessel. Well B is equipped
with a proper wellhead and safety means. The casing of well B may
be used as a storage tank for high pressure gas supply. The source
for high pressure gas can also be a high pressure gas producing
well or a gas sales line. Compressor C compresses gas from well A
or other gas sources into the casing of well B to maintain the
required pressurized gas volume in well B. A lower flow control
valve 120, which in this embodiment is shown as check valve, is
installed within the tubing 104 above packer 102 to prevent the
downward flow of fluids within tubing 104.
An upper flow control valve 70 is disposed within the tubing 104
above the lower flow control valve 120. The upper flow control
valve 70 is closed when desired to block the upward flow of fluids
in the tubing 104. The setting depth of the upper flow control
valve 70 is determined and optimized by the volume of liquids that
has accumulated in the tubing 104 which cause the well to approach
the "load up" condition. This liquid level limit can be determined
by appropriate well tests such as bottom hole flowing pressure
tests, and tests to determine the liquid level in the tubing.
Several methods can be used to open or close the upper flow control
valve 70. FIG. 1 shows one method in which the opening and the
closing of the upper flow control valve 70 is controlled by the
fluid pressure within the gas supply line 107 which extends in the
casing annulus 130 from the surface.
A controller 108 is provided to initiate and control the operation
of the system of FIG. 1. The controller 108 can be a microprocessor
which controls the operation of the system of FIG. 1 based on the
downhole fluid pressure differential in the tubing 104, or the
controller 108 can be a timer controller which initiates and
controls the operation of the system of FIG. 1 based on regularly
timed cycles.
The microprocessor controller 108 receives electronic signals
(milli amp or milli volt) from suitable pressure transmitters
transmitting fluid pressure at different locations inside the
tubing 104. The pressure transmitters may be connected to the well
tubing 104 above packer 102 to communicate pressure conditions at
different locations inside the tubing 104 to the controller 108.
FIG. 1 shows the pressure transmitters G1, G2, and G3 which are in
communication with the surface controller 108 via cable 114.
Pressure gauge G1 is preferably connected to the tubing above the
lower control valve 120 and pressure gauges G2 and G3 are connected
to the tubing nearer to the upper flow control valve 70. The
controller 108 receives electronic signals from pressure
transmitters G1, G2, and G3. The controller 108 actuates the
actuating means of valves V1, V2, V3, V4, V5, and V6 at the surface
to cause each valve to move to its closed or open position.
The controller 108 detects the load up conditions of well A by
determining the difference between the pressures at two or more
locations in the tubing 104 such as pressures at transmitter G1 and
the surface tubing pressure. This pressure difference is indicative
of the back pressure exerted on the producing formation due to the
weight of liquids inside the tubing 104.
When the back pressure due to the weight of the accumulated liquids
in the tubing 104 exceeds a preset amount, the controller starts
the liquid disposal process by actuating valves V3 and V6 to their
closed positions to shut in well A. Prior to the start of the
disposal process, valves V1, V2 and V4 are in their closed
positions. The controller 108 then actuates valve V1 to its open
position to allow pressurized gas to flow through the gas supply
line 107. The pressurized gas enters the variable capacity pressure
chamber 79 of the upper flow control valve 70 through port means 81
to actuate the upper flow control valve 70 to its closed position.
The supply line 107 is also connected to port 64 through which the
fluid pressure in the supply line 107 communicates with the gas
pressure dome 51 of the equalizing valve means 50. The gas pressure
in the supply line 107 maintains the equalizing valve means 50 in
its closed position. Then the injection gas enters into the fluid
injection control valve 30 which is a pressure operated valve means
through the injection port 39. The injection gas pressure will
overcome the closing forces of the fluid injection control valve 30
and actuate it to its open position to permit the injection gas to
flow into the lower portion of the tubing string or accumulation
chamber designated as 104B which is sealed off from the upper
tubing portion 104A by the closed flapper 83 of the upper control
valve 70 and from below by lower flow control valve 120. The
injection gas pressurizes the fluids inside the accumulation
chamber 104B. The pressurized fluid forces the disposal valve 10,
which is connected to the tubing 104 above lower flow control valve
120, to its open position. The liquid in chamber 104B is displaced
through the disposal valve 10 into the casing annulus 130 and
disposed of through perforations 106 into the water bearing
formation 105. The liquid can also be forced into the casing
annulus and the accumulated liquid can be "U" tubed to surface
facilities for storage and handling.
Referring still to FIG. 1, the controller 10B determines the end of
the displacement process by monitoring the pressure differential
inside the lower tubing section or accumulation chamber 14B using
pressure signals transmitted by pressure transmitters G1 and G2.
When it is determined that the pressure differential inside the
accumulation chamber 104B is reduced to the desired level, gas
injection into the supply line 107 is terminated. At this point,
the controller 108 closes valve V1 to stop the gas injection and
then opens valve V2 to connect the supply line 107 in flow
communication with the tubing 104 to relieve the gas pressure
inside the supply line 107 into the upper section 104A of the
tubing 104. The pressure inside the supply line 107 can be reduced
further to the desired level by venting gas through valve V4. Check
valve 112 prevents back flow of gas from the tubing to the
atmosphere. When the pressure inside the supply line 107 is
reduced, the pressure inside the variable capacity pressure chamber
79 of the upper flow control valve 70, and the pressure dome 51 of
the equalizing valve 50, are also reduced. The reduction of
pressure in the dome 51 will cause the equalizing valve 50 to open
and permit gas to flow from the accumulation chamber 104B through
bypass 62, here shown to be a tube, into upper tubing section 104A
of the tubing 104 to reduce fluid pressure across the flapper 83.
The pressure equalization process continues until the opening
forces acting upon the operator tube 72 of the upper flow control
valve 70 overcome the forces due to a pressure differential that
may exist across the flapper 83 and force the flapper 83 to its
open position. Controller 108 detects the opening of the flapper 83
from the transmitted pressure differential signals received from
the pressure transmitters. For example, if excessive pressure
differential is measured by transmitters G2 and G3 across the
flapper 83, it indicates to the controller 108 that the flapper 83
is closed. When the pressure differential across the flapper 83 is
less than a preset amount indicating the opening of the flapper 83,
the controller 108 opens valve V3 to return well A to its producing
cycle for production to the sales line. The controller 108 closes
valves V2 and V4 and opens valve V6 to allow the pressure regulator
R to retain a predetermined amount of pressure in the supply line
107 to keep the equalizing valve 50 in the closed position. The
compressor C pressurizes the storage well B to the desired pressure
for the next disposal cycle. Other methods can be devised to
achieve the functions of the pressure gauges, G1, G2, G3 without
departing from the spirit of the present invention such as a liquid
level transmitter to transmit the liquid level in the lower tubing
104B or a switch that is mechanically turned on or off by the
operator tube 72 to indicate the closure or the opening of the
flapper 83. During the disposal cycle, it is possible that gas is
forced out along with liquid from the accumulation chamber 104B
into the casing annulus 130. It is desirable to periodically vent
the casing gas to the production facilities through valve V5 to
reduce the casing annulus pressure.
Referring now to FIG. 2, there is shown another embodiment of the
present invention. The water bearing formation 105 is shown in FIG.
2 below the hydrocarbon producing formation 100. Packers 102 and
111 are set above and below the hydrocarbon producing formation
100. Tubing 104 is sealed off as at 117. The tubing 104 includes a
perforated nipple 110 which allows the produced fluids to enter
into the tubing 104. The lower flow control valve 120, such as a
check valve, permits upward flow of fluids in the tubing 104 but
prevents the downward flow of such fluids. The closing and opening
of the upper flow control valve 70A is controlled by two hydraulic
control lines 115 and 116. The controller 108 initiates the liquid
disposal cycle when desired by closing valve V3 to shut in well A.
The controller 108 signals pressure manifold 118 to induce pressure
to the fluid in the control line 115. The control fluid in turn
acts on the operating means of the upper flow control valve 70A to
move the closure means of the valve 70A to its closed position. The
controller 108 closes valve V6, then opens valve V1 to allow
pressurized gas to flow through the supply line 107. The
pressurized gas enters into the lower tubing portion 104B below the
closed upper flow control valve 70A. The pressurized gas
pressurizes the fluids inside the lower tubing portion or
accumulation chamber 104B and forces the liquid from the tubing 104
into the casing annulus 130 through the disposal valve 10. When the
liquid in the casing annulus 130 rises to a sufficient height to
overcome the water bearing formation pressure, it flows downwardly
through a bypass tube 119 into the water bearing formation 105.
Check valve 113 prevents the upward flow of liquids into the bypass
119. The controller 108 closes the pressurized gas to the supply
line 107 when the differential pressure in the lower tubing section
104B is reduced to the desired level. The controller 118 then opens
valve V2 to relieve the pressure in the supply line 107 into the
upper tubing portion 104A. In the system depicted in FIG. 2, the
pressure inside the supply line 107 is reduced to open the
equalizing valve means 50 to reduce the pressure differential
across the closure means of the upper flow control valve 70A. Then
the controller 108 signals the pressure manifold 118 to relieve the
induced pressure from the control line 115 and apply a
predetermined amount of pressure to the fluid in the control line
116. The fluid pressure in the control line 116 in turn acts on the
operating means of the upper flow control valve 70A to move the
closure means of the upper flow control valve 70A to the open
position. The operating means of a flow control valve operated by
two hydraulic lines has been described. The controller then opens
valve V3 to allow the fluid flowing up the well to flow into the
sales line. Check valve 36 prevents the back flow of fluid from the
tubing 104 into the supply line 107. Using hydraulic control lines
to control the upper flow control valve 70A provides better control
in opening the flow control valve because a greater opening force
can be provided. The disadvantage is the additional expense in
providing control lines and means to pressurize the fluid in the
control lines.
Another embodiment of the invention illustrated in FIG. 2 is shown
in FIGS. 3 and 4. As in the embodiment of FIG. 2, the closing and
opening of the upper flow control valve 70A is controlled by two
hydraulic control lines 115 and 116. In the embodiments of FIGS. 3
and 4, however, the supply line 107 is used only to transfer the
high pressure gas to the accumulation chamber or lower tubing
portion 104B. In the embodiment of FIG. 2, the supply line 107 was
also used to pressure and relieve pressure for closing or opening
the valve 50. However, with a separate system controlling the valve
50, that function of the supply line 107 is not necessary. With the
two functions separated, the need for the relief of high pressure
gas from the supply line 107 is eliminated. The embodiments of
FIGS. 3 and 4 permit the size of the supply line 107 to be of a
larger diameter than if the supply line 107 is to perform both
functions. When both functions are performed, a small diameter
supply line 107 would be chosen due to the pressurizing and
depressurizing cycles. With a larger supply line 107, there is the
advantage of accelerating the transfer of the high pressure gas
into the accumulation chamber or lower tubing portion 104B for the
most efficient removal of liquids. Further, the embodiments of
FIGS. 3 and 4 eliminate the need for valves V2, V4 and 112.
As shown in the embodiment of FIG. 4, the need for the compressor C
may also be eliminated. By having a high pressure gas requirement
which is simplified and direct, an alternative source of high
pressurized gas is nitrogen. Nitrogen can be obtained in liquid
form and transported in sufficient volumes to the wellsite and can
be converted at the wellsite to high pressure gas as high as 10,000
PSI. Accordingly, nitrogen or other gases can be used to purge the
liquids in the accumulation chamber 104B by introduction of the
nitrogen or other gases through the supply line 107.
Referring now to FIG. 5, there is shown another alternative
embodiment of the present invention which provides a bypass means
for bypassing the accumulation chamber 104B while the upper flow
control valve 70A is in the closed position during the liquid
removal cycle. The bypass means includes a bypass tubing 200 which
provides fluid communication between the flow bore of that portion
of the tubing below lower flow control valve 120 and the floW bore
of the tubing 104A above the upper flow control valve 70A. Check
valve means 201 is provided in bypass tubing 200 adjacent tubing
104A to prevent the backflow of fluid from within the flow bore of
upper tubing 104A into the bypass tubing 200. Thus, the bypass
means provides fluid communication between the producing formation
100 and the upper tubing 104A above upper flow control valve 70A to
permit the release of pressure from the formation and to accelerate
production. This may be particularly beneficial for low
productivity formations. In other embodiments of the present
invention, pressure is allowed to build up below the packer 102 as
the upper flow control valve 70A is in the closed position during
the liquid removal cycle.
FIG. 6 shows still another embodiment of the apparatus of the
present invention. In this embodiment upper and lower flow control
valves 70A and 70B are used to encapsulate part or all of the
accumulated liquid in the tubing 104. The flow control valves 70A
and 70B, both normally remain in open position allowing well fluid
to flow through the tubing 104. The lower flow control valve 70B
preferably has suitable closure means such as a ball. The flow
control valves 70A and 70B can be connected to the tubing 104 at
any desired depth. The setting depth and the distance between the
flow control valves are optimized based on the amount of liquid
that must be removed from the tubing 104. When the lower flow
control valve 70B is in closed position, the tubing volume between
the closure means of the lower flow control valve 70B and the
closure means of the upper flow control valve 70A becomes the
accumulation chamber 104B. Control means are provided to
selectively control the closing and the opening of the flow control
valves 70A and 70B. For example, in FIG. 6 the flow control valves
70A and 70B are shown to be controlled by two hydraulic control
conduits 115 and 116 extending from surface of the well through the
casing annulus to the flow control valves 70A and 70B. The
hydrostatic pressure of the fluid in the control line 116 acts on
the operating means of the flow control valves 70A and 70B to
balance the hydrostatic pressure of the fluid in control line 115
which is being exerted on the operating means of the flow control
valves 70A and 70B. The flow control valves 70A and 70B each have
resilient urging means biasing each flow control valve to an open
position. The opening forces stored in the resilient urging means
of the lower flow control valve 70B is less than the opening forces
stored in the resilient urging means of the upper flow control
valve 70A. Thereby when the fluid in control line 115 is
pressurized, the lower flow control valve 70B is closed first, then
further pressurizing the fluid in control line 115 will result in
closing the upper flow control valve 70A.
In operation, the controller 108 monitors the pressure differential
at two or more locations inside the tubing 104. When this pressure
differential exceeds a present amount, the controller 108 signals
the pressure manifold 118 to induce pressure to the fluid in the
control line 115. The control fluid in turn acts on the operating
means of the lower flow control valve 70B and moves the closure
means of the lower flow control valve 70B to its closed position.
As previously stated, the closing pressure of the upper flow
control valve 70A is higher than the closing pressure of the lower
flow control valve 70B. Thereby the upper flow control valve 70A
remains in the open position and the liquid in the tubing 104 above
the lower flow control valve 70B accumulates on top of the closure
means of the lower flow control valve 70B. The controller 108
actuates valve V3 to closed position. The controller 108 signals
the pressure manifold 118 to induce additional pressure to the
fluid in the control conduit 115 to close the upper flow control
valve 70A and encapsulate the accumulated liquid in the
accumulation chamber 104B. The controller 108 then actuates valve
V1 to its open position to allow pressurized gas to flow through
the supply line 107 and open the injection control valve 30. The
pressurized gas will enter into the accumulation chamber 104B and
force the disposal valve 10, which is connected to the tubing 104
above and adjacent to the lower flow control valve 70B, to its open
position. The encapsulated liquid in the accumulation chamber 104B
is displaced through the disposal valve 10 into the casing annulus
130.
Referring still to FIG. 6, the controller 108 determines the end of
the displacement process by monitoring the pressure differential
inside the accumulation chamber 104B using pressure signals
transmitted by the pressure transmitters G1 and G2. When it is
determined that the pressure differential inside the accumulation
chamber 104B is reduced to a desired level, controller 108 stops
gas injection into the supply line 107 by actuating valve V1 to
closed position. Controller 108 actuates valves 70A and 70B to
their open position by relieving the induced pressure from the
control line 115. Pressure equalizing means may be provided to
reduce pressure across the closure means of the flow control valves
70A and 70B to ease the opening of said flow control valves.
Pressure manifold 118 may be used to induce fluid pressure into the
control line 115 to provide additional opening force and accelerate
the opening of the flow control valves 70A and 70B. The controller
108 opens valve V3 to allow the production well to produce into the
production facilities.
Another form of the liquid removal system of the present invention
employs a subsurface actuated flow control valve such as a flow
control valve described in U.S. Pat. No. 3,980,135 in place of a
surface controlled flow control valve. A subsurface controlled flow
control valve is held open by the normal downhole pressure at the
valve. It automatically closes when the downhole pressure drops
below a predetermined level. After closure, applied tubing pressure
in excess of the downhole pressure below the valve returns the
valve to the open position. When a subsurface actuated flow control
valve is used for this invention, the disposal cycle and the
pressure equalization cycle procedures are the same as previously
described with respect to the system of FIG. 1, except the
subsurface actuated flow control valve is closed automatically when
the downhole pressure at the valve depth drops below a
predetermined amount. The controller detects the closure of the
subsurface actuated flow control valve. One way the controller may
detect the closure of the subsurface actuated flow control valve is
from a decrease in the flowing tubing pressure at the surface. The
controller closes the tubing to the production facilities and
starts the liquid disposal procedure as described with respect to
the system of FIG. 1. To open the subsurface actuated flow control
valve the pressure across the closure means of the subsurface
actuated flow control valve is equalized as described with respect
to the system of FIG. 1. Then pressurized gas is introduced to the
top of the tubing from the pressurized gas source to exceed the
fluid pressure below the closed valve and force the subsurface
actuated flow control valve to its open position. This system has
the advantage of using a less expensive flow control valve than the
systems of FIG. 1 and FIG. 2. However, to open the flow control
valve, additional pressure must be supplied to the tubing which
results in a less efficient system.
The system of this invention can also employ a conventional safety
valve which is controlled by a single hydraulic control line, such
as the safety valves described in U.S. Pat. Nos. 4,376,464 and
4,161,219, to substitute the flow control valve of the system of
FIG. 2. Generally, these types of valves are biased to the closed
position and are opened in response to fluid pressure applied from
the surface through a control line. These types of safety valves
are limited in their depth of operation because resilient urging
means biasing the safety valve to a closed position must overcome
the hydrostatic head pressure in the hydraulic control line. These
types of flow control valves can be used in a liquid removal system
for a shallow well.
As stated, the present invention utilizes flow control valves to
create a temporary liquid accumulation chamber in the tubing of a
hydrocarbon producing well. Examples of fluid operated flow control
valves, better known as safety valves, may be found in U.S. Pat.
Nos. 4,252,197; 4,161,219; and 4,452,310. The present invention
includes a method to modify these types of safety valves to better
serve the objectives of the present invention. For the purpose of
illustration, the modification will be shown as incorporated in a
flapper type safety valve, such as a piston actuated well safety
valve described by Pringle in U.S. Pat. No. 4,252,197. It will be
understood that the present invention may utilize other modified
flow control valves, such as tubing retrievable, or wire line
retrievable control valves. Flow control valves having various
other types of valve closing elements, such as ball or poppet
elements, may be used. Similarly, other fluid operated valves with
a closing and opening mechanism actuated by fluid flow or fluid
pressure may be used.
Referring now to FIGS. 7A and 7B, the flow control valve 70 of the
present invention is shown as being of a tubing retrievable type.
The flow control valve 70 generally includes a valve housing 71
that permits fluid to flow through bore 77. The flow control valve
70 includes a valve closure member such as a flapper 83 which is
carried about a pivot pin 85. The flapper 83 may include a spring
84 for yieldably urging the flapper 83 about the pivot pin 85 and
onto an annular valve seat 86 which is positioned about the bore 77
for closing valve 70 to block fluid flow from the lower tubing
portion 104B to the upper tubing portion 104A.
An operator tube 72 is telescopically moveable in the housing 71
and through the valve seat 86. When the operator tube 72 is moved
downward, the operator tube 72 pushes the flapper 83 away from the
valve seat 86. Thus the flow control valve 70 is held in the open
position. When the operator tube 72 is moved upward, the flapper 83
is allowed to move upward onto the seat 86 by the action of the
spring 84. Several methods can be used to control the closing or
opening of the flow control valve 70. One method is to control the
closing and the opening of the flow control valve 70 by the
application or removal of pressurized gas through the gas supply
line 107 which is connected to the valve housing 71 at port means
81. In operation, when gas is injected into the supply line 107
from the surface, the gas pressure is applied to suitable hydraulic
fluid in the pressurizing chamber 79 through passageway means 80
and the hydraulic fluid in turn applies pressure to the lower end
of one or more pistons 76 which in turn engage the operator tube 72
such as by a tongue and groove connection 75 to move the operator
tube 72 upward causing the flapper 83 to move to its seated
position. When it is desired to open the flow control valve 70, the
fluid pressure in the supply line 107 is reduced. Any suitable
biasing means can be used such as a spring 74 or a pressurized gas
chamber (not shown), which may act between a shoulder 73 on the
valve housing 71 and against the upper end of the pistons 76 for
yieldably urging the operator tube 72 in a downward direction to
force the flapper 83 to its open position for opening the flow
control valve 70. The upper end of the pistons 76 are exposed to
the tubing pressure. Thus the tubing pressure acts on the upper end
of the pistons 76 and provides additional force to move the
operator tube 72 downward.
Referring now to FIG. 8, a further embodiment of the means for
moving the tubular member 72 to upward and downward positions is
shown. In this embodiment, hydraulic control line 116 is connected
to the valve housing 71 at port means 131. The fluid pressure
within the control line 116 communicates with the pressurizing
chamber 93 through port 131. One or more pistons 76A which are
telescopically moveable in the housing 71 are provided. The
hydraulic control line 115 is connected to the housing 71 at port
means 132. The fluid pressure within the hydraulic line 115
communicates with the pressurizing chamber 90 through port 132. The
pistons 76A move in the pressurizing chamber 93 and are sealed
therein by means of suitable seals 92. The pistons 76A can also
move in the pressurizing chamber 90 and are sealed therein by means
of suitable seals 91. Wiper means 68 are provided to prevent the
engagement of solid matter with the pistons 76A. The piston
assembly shown in FIG. 8 can be used to provide means to open and
to close the closure means of the flow control valve of this
invention in response to fluid pressure transmitted to the piston
assembly through control lines 116 and 115.
In operation of the embodiment shown in FIG. 2, when control fluid
within control line 116 is pressurized and the pressure in the
control line 115 is reduced, the pistons 76A move the operator tube
72 downwardly and the upper flow control valve 70A is opened. When
control fluid within control line 11 is pressurized and the
pressure in the control line 116 is reduced, the pistons 76A move
the operator tube 72 upwardly and the upper flow control valve 70A
closes. Hydraulically controlled actuation means of the upper flow
control valve 70A provide a better surface control for closing or
opening of the upper flow control valve 70A than the actuation
means of the upper flow control valve 70 of FIG. 1 which is
controlled by the supply line pressure.
Referring now to FIG. 9, a further embodiment of the means for
moving the tubular member 72 to upward and downward positions is
shown. In this embodiment, the hydraulic control line 115 and the
balance line 116 extend between the upper flow control valve 70A
and the surface. The hydraulic control valve 116 is connected to
the valve housing 71 at port means 131. The fluid pressure within
the control line 116 communicates with the pressurizing chamber 93
through port 131. One or more pistons 76A which are telescopically
moveable in the housing 71 are provided. The hydraulic control line
115 is connected to the housing 71 at port means 132. The fluid
pressure within the hydraulic line 115 communicates with the
pressurizing chamber 90 through port 132. The hydrostatic pressure
of the fluid in the hydraulic line 116 balances the hydrostatic
pressure of the fluid in the hydraulic control line 115. The
pistons 76A move in the pressurizing chamber 93 and are sealed
therein by means of a suitable seal 92. The pistons 76A can also
move in the pressurizing chamber 90 and are sealed therein by means
of suitable seals 91. A suitable resilient urging means such as
spring 74, which may act between a shoulder 73 on the valve housing
71 and against the upper end of the tongue and groove connection
75, for yieldably urging the operator tube 72 in a downward
direction to open the closure means of the flow control valve.
Wiper means 68 are provided to prevent the engagement of solid
matter with the pistons 76A. The piston assembly shown in FIG. 9
can be used to provide means to open and to close the closure means
of the flow control valve of this invention in response to fluid
pressure transmitted to the piston assembly through control lines
115 and 116.
In operation, due to the force of the resilient urging means 74,
the operator tube 72 is normally in the downward position causing
the closure means of the flow control valve to stay in the open
position. When desired, the fluid within control line 115 is
pressurized, causing the pistons 76A to move the operator tube 72
upwardly and the upper flow control valve 70A closes. Hydraulically
controlled actuation means of the upper flow control valve 70A
allows the valve to be set at any depth and provide a better
surface control for closing or opening of the upper flow control
valve 70A than the actuation means of the upper flow control valve
70 of FIG. 1 which is controlled by the fluid pressure in one
control line.
U.S. Pat. No. 4,376,464 describes a safety valve in which the
pistons moving the operator tube annularly surround the operator
tube of the safety valve. This type of piston assembly can be
modified for use in the flow control valve of the present invention
to provide means to move the operator tube upwardly upon
application of fluid pressure through the supply line 107 to the
piston assembly.
FIG. 10 shows a piston assembly to control the movement of the
operator tube 72. In this embodiment, suitable seals 96 and 97
provide a variable capacity pressure chamber for receiving fluid
pressure from the supply line 107. The supply line 107 is connected
at port 69 to the valve housing 71. There is a fluid passageway 98
leading from port 69 to a variable capacity chamber 99. The fluid
under pressure enters the variable capacity chamber through
passageway 98 and is confined between seals 96 and 97, but with
seal 97 carried about the circumference of the operator tube 72,
the fluid pressure causes the operator tube 72 to be moved
upwardly. Any suitable resilient urging means 74 (here shown to be
a spring) may be positioned between a shoulder 73 on the valve
housing 71 and against the shoulder 67 on the tubular member 72 for
yieldably urging the operator tube 72 in a downward direction to
force the flapper 83 to its open position. The tubing pressure also
acts on the upper end of the seal 97 and provides additional force
to move the operator tube 72 downwardly. The piston assemblies
moving the operator tube as shown in FIGS. 7A and 8 are preferred
because the flow control valve's pressurizing chamber is out of
communication with the operator tube 72, thereby eliminating the
large seals about the operator tube 72.
The present invention contemplates providing pressure equalizing
means to reduce pressure across flapper 83 before opening the flow
control valve 70. The flow control valve 70 may include an
equalizing subassembly, as shown in FIG. 11, which is opened to
equalize pressure across flapper 83. Another form of the equalizing
means as shown in FIG. 13 can be connected to the well tubing to
control bypassing of fluid pressure across flapper 83 through a
bypass means.
Referring now to FIG. 11, in this embodiment the flow control valve
70 includes the equalizing subassembly 71B. The equalizing
subassembly 71B is connectable in the flow control valve 70 between
valve housing member 71A and 71C with the equalizing subassembly
71B extending axially between the operator tube 72 and the valve
housing 71. As in U.S. Pat. No. 4,376,464, the threaded flapper
subassembly 87 to which is attached the flapper valve 83 is secured
to the equalizing subassembly 71B, by providing locking means such
as plurality of set screws (not shown). In the housing of the
equalizing subassembly 71B there is a longitudinal flowway 65 in
which is housed a suitable pressure responsive means such as a
piston rod 54 with piston seals 52 which are reciprocally moveable
therein. The valve member 54 cooperates with seat 56 to control
fluid flow through the flowway 65. The upper end of the flowway 65
is sealed by a suitable seal means such as a threaded bolt 66.
Thus, a pressurizing chamber 51 is defined between the upper end of
the piston seals 52 and the closed upper end of the flowway 65. The
supply line 107 is connected to the equalizing subassembly 71B at
port means 134. The pressurizing chamber 51 is in communication
with the supply line 107 through passageway 133. A suitable choke
means, such as threaded choke means 47 with passageway 48, is
provided in the pressurizing chamber 51. The choke 47 provides a
restriction to the flow of fluids in the pressurizing chamber 51.
Viscous silicon fluid may be injected into the pressurizing chamber
51 during valve assembly to act as a damper during valve opening.
Any suitable resilient urging means, such as a spring 49, may be
provided to act between the lower end of the choke 47 and upper end
of valve member 54 to assist in maintaining the valve member 54 in
a closed position.
In operation, the pressure in the supply line 107 acts on the upper
end of piston seals 52 and, assisted by the force of spring 49,
urges valve member 54 to its seated position. During the disposal
cycle, valve member 54 remains in a closed position because the
closing forces that are acting on the valve member 54 are greater
than the opening forces.
During the equalization process, the pressure inside the supply
line 107 is reduced to open the equalizing valve means. The tubing
pressure below the flapper 83 acts on the valve member tip 53 and
the tubing pressure above flapper 83 acts on the lower end of
piston 52 to move valve member 54 upward to its open position.
FIGS. 12A and 12B show the flow control valve 70 in its closed
position, and the equalizing subassembly 71B in its open position.
When the equalizing valve is opened, gas flows from below the
flapper 83 to the area above the flapper through passageway 65 and
through one or more equalizing ports such as 59A and 63A which are
provided in the equalizing subassembly 71B and the operator tube
72. FIG. 12B shows that the equalizing ports 63A and 59A are
aligned when the flow control valve 70 is closed and the operator
tube is in its upward position. Thus when the equalizing valve
means opens, gas will flow through the equalizing ports 59A and 63A
into the tubing.
Flapper 83 will remain in a closed position until the differential
pressure across the flapper 83 is reduced to a point that the
opening forces acting on the operator tube 72 move the operator
tube 72 downward and move the flapper 83 to its open position.
Additional pressure can be supplied to the dome 51 through the
supply line 107 to assist spring 49 to move valve member 54 to its
closed position. The pressure supplied to the dome 51 to close the
equalizing valve means is less than the pressure required to
overcome the opening forces of the flow control valve 70.
FIG. 13 shows another form of an equalizing means for connection to
the tubing 104. The equalizing valve 50 is a dome pressure operated
valve and has a housing 50A with a flowway 65A therein. The
equalizing valve 50 has a threaded outlet 59 attached to the
mandrel lug 55. The equalizing valve 50 is sealed against the
internal wall of the mandrel lug 55 using suitable seals 135. The
outlet 59 communicates with the bypass tube 62 through a check
valve 57. Check valve 57 allows flow of fluid from the outlet of
the equalizing valve 50 to the bypass tube 62 but prevents flow
from the bypass tube 62 into the well tubing. The upper end of the
bypass tube 62 is connected to the tubing 104 at port 63A. The
equalizing valve 50 has an inlet 58 communicating with the fluid
pressure inside the lower tubing portion 104B through inlet 60 of
the mandrel 55. The equalizing valve 50 has a valve member 54A
therein which cooperates with a seat 56A in the flowway 65A to
control flow through the equalizing valve 50. The equalizing valve
50 has a pressure dome 51A which is in fluid communication with the
supply line 107 through port 64. Thus, the pressure in the pressure
dome 51A may be varied by changing the pressure inside the supply
line 107. The pressure dome 51A is closed by a suitable pressure
responsive means such as bellows 52A which is connected to the
valve member 54A. The valve member 54A is moved downward to its
seated position by dome gas pressure admitted through port 64 from
the gas supply line 107 and is moved upwardly to open valve 50 by
the pressure of fluids in the tubing 104. During the production
cycle of the hydrocarbon producing well, it is desirable to keep
the equalizing valve 50 in a closed position. This can be
accomplished by maintaining fluid pressure to dome 51A through
supply line 107. It is desirable to minimize the pressure in the
supply line 107 during the production cycle of the hydrocarbon
producing well to maintain valve 50 in the closed position. This is
important when this type of equalizing means is used in a system
where the flow control valve 70 is also controlled by the pressure
in the supply line 107. The pressure in the supply line 107 during
the production cycle should be less than the pressure that will
close the flow control valve 70. The pressure required to maintain
the equalizing valve 50 during the production cycle can be
minimized by reducing the effective area where the tubing pressure
is acting to open the valve 50. Suitable seals 52B are provided to
seal off the bellows 52A from the effect of tubing pressure. Seals
52B may have a smaller area than the effective area of the bellows
52A. This will reduce the opening forces acting on the valve 50 due
to the tubing pressure.
FIG. 14 shows a wireline retrievable fluid injection control valve
30 which is similar to a dome pressure charged gas lift valve. One
or more injection control valves are used to control the admission
of pressurized gas into the accumulation chamber 104B. Valve 30 may
also be used to control the sequence of the closure of the
equalizing valve 50, closure of the flapper valve 83, and the start
of the disposal process respectively. The injection control valve
30 may be a part of the flow control valve 70 as shown in FIG. 16
or can be a separate tubing retrievable or wireline retrievable
valve for connection below the flow control valve 70 in the tubing
104 as shown in FIG. 14.
FIG. 14 shows a wireline retrievable fluid injection control valve
30 secured in the mandrel 45 using suitable lock means 137 and
suitable seal means 45A and 45B. The supply line 107 is connected
to the mandrel 45 at port 39. The valve 30 has a housing 42 with a
flowway 43. The flowway 43 has an inlet 37 communicating with the
supply line 107 through port 39. The valve 30 has a valve member 34
therein which cooperates with a seat 35 in the flowway 43 to
control flow through the injection valve 30. The valve member 34 is
urged toward a seated position by a charge of fluid under pressure
in the dome 32 of the injection control valve 30. The dome is
closed by suitable pressure responsive means such as bellows 33. In
operation, the opening forces due to gas pressure provided by the
supply line 107 acting upon bellows 33 and assisted by tubing
pressure acting upon the valve member stem tip 41, overcome the
closing forces due to the fluid pressure in the dome 32. This
causes the bellows 33 to move upward and lift the valve stem tip 41
off the valve seat 35. The injection gas is then able to flow
through the valve 30 and through outlet 38 into the lower tubing
section 104B below the closed flapper 83.
The pressure in the dome 32 is set to ensure that the injection
control valve will not open until the gas pressure from the supply
line 107 has actuated the flow control valve 70 and the equalizing
valve 50 to their closed positions. Viscous silicon fluid is
injected into the bellows 33 during valve assembly to act as a
damper during valve opening. Reverse flow through valve 30 from the
tubing 104 to the supply line 107 is prevented by a spring loaded
check valve 36. Another embodiment of the fluid injection control
assembly is shown in FIGS. 15 and 16 in which the flow control
valve 70B includes a fluid injection control subassembly. FIG. 15
shows a flow control valve 70B, of a wireline retrievable type, for
connection in a well tubing by a conventional lock 136. The flow
control valve 70B has a housing 71 adapted to be positioned in the
tubing 104 and sealed against the tubing 104 using suitable seals 5
and 6. The flow control valve 70B in addition to all the features
of the tubing retrievable flow control valve 70 as previously
described, may also include one or more fluid injection control
subassemblies. FIG. 16 shows the injection control subassembly 71D
for connection to the flow control valve 70B. The injection control
subassembly 71D is connectable in the flow control valve 70B
between valve housing members 71C and 71E. There is preferably
disposed within said injection control subassembly 71D, a flowway
43A. Within flowway 43A is housed a valve member 34A cooperating
with seat 35A in the flowway 43A to control flow of fluid in the
flowway 43A. The supply line 107 is connected to the injection port
39 which is provided in the tubing 104. The flowway 43A has an
inlet 44 which is exposed to the pressure in the supply line 107.
The flowway 43A has an outlet 38A leading into the tubing 104.
Valve member 34A includes pressure responsive means, such as piston
33A, capable of longitudinal sliding movement within the dome gas
chamber 32A. The dome 32A is pressurized to a desired pressure
through passageway 31 during valve assembly. The valve member 34A
is urged to a downward and seated position by the pressure in the
dome gas chamber 32A. In operation, the injection gas from the
supply line 107 enters into the annulus 20A and through port 81
(shown in FIG. 15) into the pressure chamber 79 of the flow control
valve 70B to close the valve 70B. When the opening forces acting on
the piston 33A due to the gas pressure in the supply line 107
exceed the closing forces acting on the valve member 34A, valve
member 34A moves upward and permits gas to flow from inlet 44
through outlet 38A into lower tubing section 104B to pressurize the
fluid in the accumulation chamber 104B and force the liquids from
the accumulation chamber 104B through a disposal valve to the
casing annulus. Reverse flow through the injection valve
subassembly 71D is prevented by a check valve 36.
FIG. 17 illustrates a wireline retrievable disposal valve 10
secured in the mandrel 19 using suitable lock means 21 and suitable
seals 13 and 14. Valve 10 is a relief valve, which can be of a
tubing retrievable or wireline retrievable type. The disposal valve
10 controls flow of fluid from the tubing into the casing annulus.
The disposal valve 10 is a dome pressure charged and/or spring
loaded relief valve which is subjected on one side to the fluid
pressure in the interior of the tubing 104 and on the other side to
the fluid pressure in the annulus 130. Valve 10 is preset to a
desired opening pressure and will open to allow fluid to pass from
the interior of the tubing 104 to the annulus 130 when the pressure
inside the tubing 104 exceeds the pressure in the annulus by the
preset amount. One or more disposal valves can be used to achieve
the above objectives.
Referring to FIGS. 1 and 17, in operation, injection gas enters
into the lower tubing section 104B, which is sealed off from the
upper tubing section 104A by the closed flapper 83. The injection
gas pressure and the hydrostatic pressure of the liquids in the
lower tubing section 104B force the bellows 12 and the valve member
16 to move upwardly to let fluid from port 17 pass through seat 15
and through disposal port 18 to the annulus 130 for disposal. Check
valve 22 is provided to prevent back flow of fluid from annulus 130
into the tubing 104.
Thus, it has been demonstrated that the method of present invention
provides an advantage over the prior art in that the pressurized
gas volume required to dispose of the undesired liquid from the
well tubing is minimized and a better surface control is provided
to control the frequency of the dewatering cycle of the hydrocarbon
producing well.
While preferred embodiments of the invention have been shown and
described, modifications thereof can be made by one skilled in the
art without departing from the spirit of the invention.
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